Study On The Effects Of Compound Improver On Bread Quality And Its Mechanism

Bread is easy to deteriorate during storage,resulting in higher hardness and water loss,so that it is usually improved by adding improvers.However,there are still many problems of the existing improvers,such as the effects are not up to expectation,the improvement effects are not comprehensive enough.In this paper,the effects of fungalα-amylase（FA）,glucose oxidase（GOD）,glucoamylase（GA）,lipase（LP）,cyclodextrin glycosyltransferase（CGT）,diacetyl tartaric acid ester of mono（di）glycerides（DATEM）,and sodium stearyl lactylate（SSL）on bread qualities were investigated,and the formula for compound improver was optimized on the basis of the research on interaction,then the effects of compound improver on the bread baking qualities were explored,at last the improvement mechanism of the compound improver was discussed from three aspects of dough rheological properties,starch crystallinity,and water distribution and migration.The main research contents and results are as follows:Firstly,the single factor experiment was carried out with the hardness,moisture content,and specific volume of bread as the indicators.The results showed that the seven improvers all could significantly reduce the hardness of bread crumbs stored for 7 days（p<0.05）;all improvers except FA could increase the moisture content of bread crumbs stored for 7 days（p<0.05）;the seven improvers all had the effect of increasing the specific volume of bread.On this basis,taking the hardness of crumbs as an indicator,the formula for the compound improver which was optimized by an orthogonal experiment was:1 mg/kg FA,10 mg/kg GOD,5 mg/kg GA,6 mg/kg LP,0.4 m L/kg CGT,0.5 g/kg DATEM,and 0.1 g/kg SSL.Secondly,the effects of compound improver on texture,moisture,specific volume,flavor,sensory,color,and tissue texture of bread were explored.Compared with the blank bread,the hardness and chewiness of crumbs with the compound improver were significantly reduced by 21.91%and 18.62%respectively after 30 days of storage（p<0.05）,and the moisture content of crumbs with the compound improver was significantly higher from 1 to 7 days of storage（p<0.05）,and the specific volume of the bread with the compound improver was significantly increased by 12.94%（p<0.05）,and the types and contents of aldehydes and ketones in volatile flavor compounds of bread with the compound improver was increased,and the overall sensory evaluation of consumers in bread with the compound improver was raised.Compared with the bread with commercially available improver,the hardness of crumbs with the compound improver were significantly reduced by 4.91%（p<0.05）,and the specific volume of the bread was increased by 0.13 m L/g（p<0.05）.FA,GA,DATEM,and SSL all could significantly increase the a*of crusts and the porosity of cross-sections.Based on this,when the compound improver was applied to bread,the a*of crusts,the pore density and porosity of cross-sections were significantly increased by 13.72%,15.61%,and 12.76%,respectively（p<0.05）,indicating that the compound improver promoted the Maillard reaction of crusts and enhanced the gas production activity of yeast.Finally,according to the effects of single improver,the effects of the compound improver on the dough characteristics,bread anti-staling,bread water retention capability,and its possible mechanism were explored.Not only the formation time,stabilization time,tensile energy,and maximum tensile strength of the dough with compound improver were significantly increased by 9.44%,17.50%,21.17%,and 39.75%respectively（p<0.05）,but also the storage modulus and loss modulus of the dough had been somewhat enhanced,indicating that the compound improver had the effect of enhancing gluten so that the machinability and rheological properties of the dough were effectively improved.Compared with the bread with commercially available improver,the starch relative crystallinity and retrogradation enthalpy of bread with the compound improver significantly decreased by 9.26%and 31.76%（p<0.05）after stored for 7 days respectively,which were also obviously lower than those of blank bread,indicating the compound improver inhibited the migration and agglomerate of starch chains,then delayed the recrystallization process of starch,thereby enhancing the anti-staling capability of bread.The water activity of bread with the compound improver decreased significantly on the first 5 days of storage,and the moisture from T₂₁ to T₂₂ was less than blank bread,indicating that the compound improver enhanced the water retention capability of bread,and hindered the transformation of strongly bound water to weakly bound water,so that the migration of moisture from the gluten area to the starch area was inhibited,resulting in the available moisture for starch crystallization reducing.In conclusion,the formula for the compound improver optimized in this paper can significantly improve the dough properties,bread baking qualities,bread storage properties,and provide reference for the production of bread with strong anti-staling and water retention capability,which has good practicability.